We’re discussing various ways to transfer files using the Iridium satellite network from our gizmo floating around in the ocean to shore. We have a lot of experience with Iridium and it is pretty much the only choice for our needs. Speed isn’t the issue since Iridium is only 2400 baud. We do need robust error detection and re-transmission of bad packets. Our files are typically in the 40KByte to 100KByte size range. We do lose the Iridium connection for minutes at a time on a regular basis so being able to pick up a transfer without starting at the beginning after losing the link is important. Another factor is Iridium probably has an error rate several orders of magnitude higher than most other connections.
We’ve looked at a variety of protocols and are leaning toward porting Industrial ZModem ( http://www.omen.com/ind.html ) to C#. This is do-able but won’t be easy because iZModem uses a variety of tricky bits that work in C but aren’t available in C#.
We haven’t been able to find a C# version of ZModem, does anyone know of one?
Is NETMF FTP a better choice for Iridium? (maybe the one under discussion in https://www.ghielectronics.com/community/forum/topic?id=14270 )
I’d value any input.